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Dr. Robert Gillespie


Department of Biology


Out of the 300 genera of freshwater mussels (Family: Unionidae) represented in North America, most species have exhibited declines in abundance and distribution largely due to anthropogenic impacts. We compared community composition, abundance and richness of mussels in Cedar Creek, Indiana in 2015 with those in 1988 and 2005. In 2015, five sites in Cedar Creek and seven sites in agricultural tributaries were surveyed. Additionally, one headwater stream in Hillsdale County, Michigan was surveyed as a high-quality reference site. At each 200 m long site, mussels were sampled with quadrats (sixteen per site) and visual searches. From each quadrat, a quart of sediment was retained for sediment analysis. Physicochemical measurements, habitat analyses, and water quality data were collected concurrently with surveys. Fishes were sampled using electrofishing to document the presence of fish host species. Out of thirteen sites sampled in 2015, only six had live mussels. Ten species and 84 individuals were identified and measured from these six sites. The reference and two Cedar Creek sites comprised almost 90% of the individuals found, with the furthest upstream Cedar Creek site having the greatest abundance (28). Only two agricultural drainage ditch sites that were located close to the main stem of Cedar Creek had mussels and only six individuals were found. Lampsilis siliquoidea occurred found at four sites in 2015 and was the most abundant and widespread species comprising 31% of the individuals found. The abundance of live mussels within four Cedar Creek main stem sites exhibited a progressive decline from 168 individuals in 1998 to 110 in 2005 to 56 in 2015. Additionally, since 1988, no live mussels have been recorded in Cedar Creek between Waterloo and Auburn, Indiana. To assess possible causes of declines, we will evaluate the relationships of instream habitat, physicochemical, and water chemistry variables with mussel abundance and species richness. A previous study in Cedar Creek found evidence of a lack of recruitment in L. siliquoidea populations. Therefore, declines in adult mussels may have resulted from the effects of deteriorating water and habitat quality on survival of larval and juvenile stages in Cedar Creek.



Comparison of Freshwater Mussel Communities from 1988 to 2015 in the Cedar Creek Watershed, Indiana

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